Photosystem 2 photochemistry and pigment composition of Dicranopteris dichotoma Bernh under different irradiances
The distribution of rare earth elements (REEs) in the lamina and chloroplast of fern Dicranopteris dichotoma Bernh from a light rare earth elements mine (LRM) and a non-mining (NM) area in Longnan county of Jiangxi province, China, were investigated by means of inductively coupled plasma-mass spectrometry (ICP-MS). The photosynthetic characteristics and pigment composition in immature and mature leaves of D. dichotoma were studied by chlorophyll (Chl) a fluorescence kinetics and high performance liquid chromatography (HPLC). Results show that contents of REEs in the lamina and chloroplast of D. dichotoma in LRM were higher than those ferns in NM. By comparing with D. dichotoma from NM area, the efficiency of photosystem 2 photochemistry and electron transport rate were significantly enhanced in mature lamina of the plant from LRM because D. dichotoma could change its xanthophyll cycle content to avoid the damaging effect of high REEs content. However, high irradiance decreased the photosystem 2 photochemistry efficiency in lamina from ferns in LRM suggested that large amount of REEs reduce the capacities to avoid photo damage in D. dichotoma.
Key words: Dicranopteris dichotoma, photoinhibition, rare earth element, xanthophylls.